RESUMEN
The arabinogalactan in the representative softwood biomass of larch was degraded using an environmentally friendly hydrogen peroxide and vitamin C (H2O2-VC) system to improve its immunomodulatory activity. Through the H2O2-VC degradation mechanism, hydroxyl radicals are generated, which then target the hydrogen atoms within polysaccharides, resulting in the breaking of glycosidic bonds. Given the impact of oxidative degradation on polysaccharides, we identified three specific arabinogalactan degradation products distinguished by their arabinosyl side chain compositions. The primary structures of the degradation products were investigated using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Congo red staining showed that the degradation products were absent in the triple-helix structure. The results of the in vitro immunological experiments indicated that an appropriate reduction in the molar ratio of arabinose to galactose enhanced the immunostimulatory effects on RAW 264.7 cells. In addition, the immunostimulatory pathway mediated by arabinogalactan was explored by toll-like receptor 4 (TLR4) inhibitor (TAK-242) These findings provide novel insights into the understanding of the relationship between the structure of arabinogalactan and its biological activity.
RESUMEN
The effect of ultrasonic intensity (28.14, 70.35, and 112.56 W/cm2) on Lignosus rhinocerotis polysaccharide (LRP) degraded by ultrasound assisted H2O2/Vc system (U-H/V) was investigated. U-H/V broke the molecular chain of LRP and improved the conformational flexibility, decreasing the molecular weight, intrinsic viscosity ([η]) and particle size. The functional groups and hyperbranched structure of LRP were almost stable after U-H/V treatment, however, the triple helix structure of LRP was partially disrupted. With increasing ultrasonic intensity, the critical aggregation concentration increased from 0.59 mg/mL to 1.57 mg/mL, and the hydrophobic microdomains reduced. Furthermore, the LRP treated with U-H/V significantly inhibited HepG2 cell proliferation by inducing apoptosis. The increase in antitumor activity of LRP was closely associated with the reduction of molecular weight, [η], particle size and hydrophobic microdomains. These results revealed that U-H/V treatment facilitates the degradation of LRP and provides a better insight into the structure-antitumor activity relationship of LRP.
Asunto(s)
Apoptosis , Proliferación Celular , Peróxido de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Polisacáridos , Polisacáridos/química , Polisacáridos/farmacología , Humanos , Peróxido de Hidrógeno/química , Células Hep G2 , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Antineoplásicos/química , Antineoplásicos/farmacología , Peso Molecular , Tamaño de la Partícula , Helechos/química , Ondas UltrasónicasRESUMEN
In this study, H2O2-Vc (hydrogen peroxide-ascorbic acid) oxidation system under 50 and 70 °C was developed to degrade blue honeysuckle polysaccharides. The results suggested that viscosity-average molecular weight was decreased and reducing sugar content was raised with the rise of time or temperature. The degradation was fitted to the second-order reaction kinetics. The gas chromatography revealed two degraded polysaccharides were consisted of six monosaccharides (Gal A, Rha, Ala, Gal, Glu, Man) with different ratios, and eight types of sugar residues were confirmed using nuclear magnetic resonance. Based on the linearity (R1), branching (R2), branch size (R3) calculation, PD70 (purified degraded polysaccharide at 70 °C) had a more linear structure and longer side chains comparing to PD50 (purified degraded polysaccharide at 50 °C). The absence of triple helical structure and sheet-like aggregation with rough surface were confirmed by the Congo red test and scanning electron. Rheological characterization proved the two degraded polysaccharides exhibited shear-thinning behavior and viscoelastic property. Besides, the two degraded polysaccharides displayed strong antiglycation activities, inhibitory effects against α-amylase and α-glucosidase, and exhibited competitive inhibitory kinetics. These findings support the potential application of blue honeysuckle polysaccharides as the treatment of diabetes.